8 PEOCEEDINGS OF THE NATIONAL MUSEUM vol. 72 



in North America, Haplophthcdiivus msngei Zaddach. This species 

 also is widely distributed in Europe which, in part at least, is due to 

 the spread of culture, and in the south of Sweden the two species are 

 not uncommonly to be found together, H. mengei is more fully 

 discussed in Sars's excellent account (1899, pp. 167-168, pi. 72, fig. 1). 



Family SCYPHACIDAE Chilton, 1901 



DETONELLA, new genus 



Body oblong oval, rather convex, epimera moderately developed. 

 Pleon not abruptly narrower than pereion, last segment short, apex 

 rounded. Dorsal surface with transverse rows of tubercles which 

 are more developed in the male than the female. Head with large 

 lateral lobes. 



Eyes small but distinct and prominent, composed of few ocelli. 



Antennulae with well-developed sensory plumose bristles at the 

 second joint besides the usual sensorj'^ filaments at the third. 



Antennae with four-jointed flagellum. 



Mandibles with a bunch of stiff hairs at the base of the inner cut- 

 ting edge, left mandible with three recurved brush-like setae and 

 right with two. Molar process represented by a dense tuft of long 

 plumose setae. 



First maxillae with the outer lobe terminating in about 10 strongly 

 chitinous spines, five of which are bifid, inner lobe bearing at the end 

 two brush-like, subequal setae. 



Second maxillae distinctly bilobed at the apex, outer lobe being 

 much smaller than the inner. 



Maxillipeds with palp longer than masticatory lobe. Palp lobed 

 on the inner side, indicating that it consists of four joints, each lobe 

 bearing a large number of stout setae. Masticatory lobe rectangular, 

 rounded, truncate at the extremity, covered with fine setae and a few 

 strong spines and bearing at its inner angle a plumose seta. 



Legs rather short, increasing little in length posteriorly. 



Penis bilobed at the apex. 



Pleopoda simple, very different in shape and structure in male and 

 female; in the former the inner dorsal surface of the exopodites 

 bears a great number of long plumose setae Avhich are lacking in the 

 latter. 



Uropoda produced, reaching considerably beyond the terminal 

 segment, rami subequal in length but the inner one much the 

 narrower. 



Remarhs. — The genus described above manifests in all essential 

 characteristics so near an agreement with the genus Deto (Guerin) 

 Chilton that I have created it only with some hesitation. Many 

 differences, however, are to be found which seem to require the 

 separation of the genus DetoneUa. It is also to be noted that all 



